Stethoscopes are traditional medical instruments that allow doctors and other healthcare professionals to listen to sounds within a patient's body. The doctor typically holds the listening piece (with a bell and diaphragm) up the patient's heart or lungs or other area to listen to sounds within the body that cannot be heard externally. The sounds are transmitted through the listening piece up through a binaural earpiece to the doctor's ears. These sounds may give the doctor an idea of what is going on within the patient's body, and may be critical in providing a proper diagnosis. In some cases, the stethoscope may be entirely mechanical. In other cases, the stethoscope may include analog or digital parts.